A $300-$400 turntable tweak

I most frequently use a Marantz TT-1000 direct-drive turntable with a bonded-on graphite mat and a Graham Phantom II tonearm.

In the past I tried a variety of clamps of varying construction, material and weight on this turntable, and have found that heavier isn't always better. In fact, usually it wasn't.

Today I am using a clamp that has adjustable clamping force. The clamp itself is fairly light and simply drops onto the record label (like a gravity clamp). Internally, however, there is a neodymium magnet which is positioned above the turntable spindle (which is normally steel). The magnet is mounted on a fine-pitch screw mechanism which allows the distance between the magnet and the turntable spindle to be adjusted in very fine increments. If the distance between magnet and spindle increases, the clamping force decreases, and if the distance decreases, the clamping force increases.

Since the screw mechanism that adjusts the magnet has nothing that binds directly to the turntable spindle, the clamping force doesn't need to be reset every time the clamp is removed from the record (unlike a normal threaded clamp).

With this clamp I have been able to experiment with clamping force and sound quality. I find that I prefer the sound when the total clamping force isn't so high. I'd guess that the clamp weighs about 200~250 grams, and I usually have the magnet set so that it adds another 250 grams or so (estimated). The clamp can be set for much higher clamping force that what I typically have it at, but I find that the sound quality starts becoming compressed both in dynamics and timbre when the clamping force is too high. Maybe someone who can't stomach any trace of edginess at all in their sound would like this. Me, I find it the sound less emotionally involving, less intellectually interesting, and far too polite.

Sonically, the difference can be pretty big. Enough to make you come to different conclusions about the same piece of equipment (or LP pressing).

I also find that some LPs benefit from less clamping force than others - it seems to vary according to label and production era.

OTOH, I have not found that leaving the clamp off completely is better - a certain amount of clamping force, but in moderation, is what I find to work best (in my audio system).

If any of you have a clamp which allows fine adjustments to the clamping force, I encourage you to experiment and experience for yourself how the sound changes.

cheers, jonathan carr

Interesting Jonathan,
Have you also ever tried a peripheral rim weight?
Cheers
Henry

Hi Henry:

Yes, I've tried various peripheral rim clamps and vacuum clamps (both add-ons and integral). In this case I found that I usually preferred the sound without peripheral or vacuum clamps. Even on my Micro-Seiki SZ-1S, which has a 28kg machined stainless-steel platter and integral vacuum clamp as well as air bearings for the platter and motor/flywheel, I ended up keeping the air bearings engaged and defeating the vacuum clamp (although I did prefer to insert a mat between LP and platter surface).

However, this is probably due to the fact that I own very few warped LPs. If I had more warped discs, I suspect that I would feel a greater fondness for peripheral or vacuum clamps.

In fairness, none of the peripheral or vacuum clamps that I have used offered such fine-grained control over the clamping force as my adjustable magnetic center clamp. I suppose that I could design such a peripheral clamp, but I have far too much on my design plate already!

cheers, jonathan

Dear Jcarr: From your lates post: could I infer then that the subject is not if the peripheral or vacuum clamp or even " normal " clamps are good or not but the " range/level "/push-down force ( quantity. ) of control?

Regards and enjoy the music,
Raul.

One more story - FWIW

A few years ago I bought a center weight to try in place of the threaded clamp on my VPI TNT. Did it make a difference – not sure. It did look nicer spinning around especially when the light caught it. It also did make the dishwarp records worse - since it was strictly a weight concentrated on the middle so the lp edges rose more. That is a fact that I didn’t realize till I brought it home. It bothered me that the manufacturer who must have known this didn’t say anything to me about it.

So I saw that another niche was created and ring peripheral weights had come out. Being a crazy audiophile guy I was ready to buy one of those rings too :( but it would not fit on either of my VPI or SP10 platters because my tonearm design was too close for clearance. So never got that far like some of you. Now from what I am reading maybe it was a good thing.

So I have tried a few more various center weights like all of us – and have gotten to the point where I don’t use any of them anymore except the following basic clamps for dish warp records. They are cheap and allow u to exert the force required to flatten the dishwarp record.

The standard vpi rubber washer/ threaded clamp for threaded spindles.

The michell record clamp is a clone or like the VPI one for threadless spindles and I use it on my sp10.

Both of the above clamps cure for me the slightly warped/dish warped lps. Many more modern records 70’s - 80’s and newer are dish warped because they are so thin as we know.

My records are also not that bad. If I had one or two that one of these basic clamps did not cure enough to play I would replace it or not play it.

Hope this helps at least one person.
YMMV

Cheers